Peripheral clear cell cholangiocarcinoma: a rare histologic variant.

We present the case of a 50-year-old diabetic male who underwent open cholecystectomy for acute gangrenous cholecystitis. At the time of exploration, a 1.5-cm mass was found peripherally in the right lobe of his liver, and an incisional biopsy was performed. Microscopic examination revealed a distinct overgrowth of clear cells in an acinar pattern, with tumor cells emerging directly from bile ducts. The tumor cells were periodic acid-Schiff reactive and diastase resistant, indicating the presence of mucin. No bile canaliculi were demonstrated by immunostaining with carcinoembryonic antigen. CT scans of the chest and abdomen were otherwise normal. Based on these microscopic, immunohistochemical, and clinical data, a diagnosis of clear cell cholangiocarcinoma was established. The patient later underwent reexploration and generous hepatic wedge resection. He did well postoperatively and is free of disease after 12 months.